1. Field of the Invention
This invention relates generally to an over-the-wire catheter, and more particularly to an over-the-wire catheter which may be simply and rapidly removed while a guidewire remains in place without use of an exchange wire or extension mechanism.
2. Brief Description of the Prior Art
Various configurations of catheters and guidewires have been developed over the years for the purpose of satisfying different functional requirements. "Over-the-wire" catheter systems permit full rotational and full coaxial mobility of the guidewire relative to the catheter component of the system. "Over-the-wire" catheters can be fully withdrawn over a guidewire, and they will accept the antegrade and retrograde introduction of a guidewire therethrough. U.S. Pat. No. 4,323,071 describes an "over-the-wire" system.
While "over-the-wire" systems allow for removal of catheters along a fixed guidewire, such removal is mechanically difficult because "over-the-wire" systems require that an exchange wire or other extension mechanism protrude from the patient's body by a length greater than the length of the catheter. Thus, manipulation of the catheter and guidewire during catheter removal is complicated.
A different type of catheter-guidewire system has been developed to address this problem. Known generically as "rapid exchange" or "monorail" catheters, the design permits catheter removal over a standard 175 cm length guidewire. U.S. Pat. Nos. 4,762,129 to Bonzel, 4,748,982 to Horzewski et al., and 5,040,548 to Yock teach variations of such designs. The designs include an inflation lumen within the catheter which runs the length of the catheter, and a separate guidewire lumen which extends a relatively short distance from the distal end toward the proximal end of the catheter. Horzewski et al. describe use of a slit in the guidewire lumen to further reduce the closed length of the guidewire lumen. Since the guidewire lumen is relatively short compared to the overall length of the catheter, when a catheter is withdrawn over the guidewire and replaced with another guidewire, a guidewire extension is not required.
The "monorail" concept has been readily accepted because it permits simple and rapid catheter removal. However, a major problem of the design is that once a "monorail" catheter has been positioned, the guidewire is extremely difficult to exchange. This is because the guidewire lumen is relatively short. When the catheter is in place and the guidewire is withdrawn, it is impractical to locate the guidewire lumen with a replacement guidewire while the "monorail" catheter (and entrance to the guidewire lumen) is within a patient's body.
Crittenden et al., U.S. Patent No. 4,988,356, have addressed this problem with a catheter system including a guidewire lumen which is slit longitudinally along the length of the catheter and a guide member which serves to spread the slit of the guidewire lumen to guide the guidewire into or out of the slit lumen. The system acts in zipper-like fashion over the length of the catheter.